1. Field of the Invention
The invention relates to a device with a memory function for controlling the closure of vehicle doors. In particular, the invention pertains to a device that is disposed around a vehicle door for detection, so that passengers can be prevented from being accidentally hurt by closing doors. The method thereof is also disclosed.
2. Description of Related Art
In mass transportation, it often happens that passengers are hurt by closing doors. For example, a bus usually has a front door and a rear door. The open, and close of the doors are controlled by the driver. To prevent the doors from hurting people or objects as they close, the driver has to check whether any person or object is in the vicinity of the door area through a rear mirror inside the vehicle or a side minor outside the vehicle. If there are many people inside the bus the driver's vision may be blocked so that the door is closed at the wrong timing to hurt passengers. This is particularly so for the rear door. If passengers are still getting on and off the bus, they may be hurt by the closing door. Such accidents happen all the time.
One solution is to install a camera near the door and a small monitor by the driver. However, this method requires the use of monitor and camera that involve a higher cost. Moreover, the camera may capture inappropriate images of ladies in summer time. Therefore, it is not widely used.
Another solution is to install a sensor on the door (similar to the elevator). If some person or object is squeezed by the door as it closes, the door automatically opens. However, if the pinched is a soft object such as a backpack belt, a scarf, or the edge of a skirt, then the above-mentioned sensor may not be able to detect it. Therefore, this is unsafe to people getting off the vehicle. For example, the passenger may be pulled by the vehicle because his/her backpack belt is held by the door.
A third solution is to install infrared (IR) or ultrasonic wave sensors above the door. When a person stands at the door, it notifies the driver not to close the door. Nevertheless, if the bus is crowded with people, the IR or ultrasonic wave sensor may incorrectly detect people or objects in the vicinity of the door, resulting erroneous reports.